datas = {
    "users" : None,
    "pois" : None,
    "acts" : None,
    "C" : None,
    "W" : None,
    "Pu" : None,
    "Pg" : None,
    "Su" : {},
    "Sg" : {},
    "S" : {},
    "P" : {},
    "result" : None,
    "a" : None,
    "b" : None,
    "alpha" : None,
    "user_dict" : {},
    "poi_dict" : {},
    "iwent" : {},
    "original_acts" : None,
    "train_alpha" : {}
}